Color stabilized poly-alpha-olefin compositions



United States Patent Ofilice 3,349,553 Patented Oct. 24, 1967 3,349,059COLOR STABiL-EZED POLY-oc-ULEFIN COMPOSITIONS Gerald R. Lappin,Kingsport, Tenn, assignor to Eastman Kodak Company, Rochester, N.Y., acorporation of New Jersey N Drawing. (Iontinuation of application Ser.No. 127,105, July 27, 1961. This application Aug. 19, 1966, Ser. No.573,725

12 Claims. (Cl. 260-4585) ABSTRACT OF THE DESCLGSURE A stabilizedplastic composition comp-rising a poly-aolefin containing a trace amountof a metallic polymerization catalyst residue, a bisphenol antioxidantand a diethanolamine.

This application is a continuation of application Ser. No. 127,105,filed July 27, 1961, now abandoned.

This invention relates to plastic compositions. More particularly, itrelates to poly-u-olefin compositions.

Poly-u-olefin polymers such as polyethylene and polypropylene undergo aphotochemical degradation when exposed to sunlight, particularlyultraviolet light, and air. This effect is frequently termed weathering.It appears to be a photo-oxidation process which causes rupture of thepolymer chains and formation of carbonyl groups. As it progresses,articles manufactured from these polymers tend to crack, become brittleand lose tensile strength to the extent of mechanical failure.Consequently, it is customary to add to poly-a-olefin polymers anadditive which functions to retard or suppress this photo-oxidationeffect. One type of additive commonly used functions to suppressphoto-oxidation by absorbing ultraviolet light. Another type of additivegenerally incorporated into these polymers functions to retardphoto-oxidation by inhibiting oxygen. For this reason this type ofadditive is referred to as an antioxidant. Some additives function byboth ultraviolet light absorption and inhibition of oxygen. The problemwhich this invention solves concerns poly-a-olefin compositionscontaining an antioxidant type of additive.

Bisphenol type compounds are quite effective antioxidants relative topoly-u-olefin polymers. However, these polymers frequently contain attrace concentrations a metallic composition which appears to form ahighly colored complex with bisphenol antioxidants. This metalliccomponent, hereinafter referred to as a metallic color former, usuallyis the residue remaining in the polymer of the metallic, polymerizationcatalyst composition employed in the synthesis of the polymer. It hasbeen found that when a bisphenol antioxidant is incorporated into apoly-u-olefin polymer Containing at trace concentrations a metalliccolor former, the resulting plastic composition tends to develop adifferent color. In most cases this effect is undesirable and notwanted.

Hence, the problem which this invention solves is how to color stabilizepoly-a-olefin compositions containing a metallic color former at traceconcentrations and a bisphenol antioxidant.

An object of this invention is to provide a solution to this problem.

A specific object of this invention is to color stabilize with anadditive polya-olefin plastic compositions containing a metallic colorformer at trace concentrations and a bisphenol antioxidant.

Another specific object of this invention is to provide suchpoly-a-olefin plastic compositions with a color stabilizer additive thatis compatible with the polymer in that it does not exude therefrom.

These and other objects are achieved by this invention which is based onmy discovery that certain diethanolamines suppress the development ofcolor in poly-a-olefin compositions comprising a bisphenol antioxidantand a color former metallic component.

in summary, this invention broadly comprises a plastic compositionconsisting essentially of (l) a poly-a-olefin polymeric componentcontaining a metallic color former at trace concentrations, (2) abisphenol antioxidant component and (3) a diethanolamine of molecularweight in excess of about two hundred and compatible with saidPOlY-oc-Olflfill polymeric component.

The poly-a-olefin polymeric component of the generic composition of thisinvention comprises one or more high or low density, normally solid,homopolymers or copolymers of a-monoolefinic aliphatic hydrocarbonshaving 2-10 carbon atoms. Examples of such poly-a-olefin polymers arethe homopolymers and copolymers of ethylene, propylene, butened,isobutylene, pentene-l, Z-methylbutene-l, 3- methylbutene-l, hexene-l,heptene-l, octene-l, nonene-l, decene-l, 4-methylpentene-l,4-methylhexene-l, 5-ethylhexene-l, 6-methylheptene-l, 6-ethylheptene-1and the like. Processes for preparing these polymers are well known andneed not be described here in detail. Reference is made to the U.S.Patent, No. 2,912,424, of Cash and the U.S. Patent, No. 2,917,500, ofHagemeyer et al. for descriptions of typical catalytic processes for thepreparation of homopolymers and copolymers of these poly-orolefins. Ingeneral, the normally solid polymers of this invention are thermoplasticsubstances having average molecular weights of at least about ninethousand. In the average molecular weight range from about nine thousandto about twelve thousand the normally solid poly-u-olefin polmersgenerally are wax-like at room temperature while above an averagemolecular weight of about twelve thousand the normally solidpoly-a-olefin polymers generally are wax-like at room temperature whileabove an average molecular Weight of about twelve thousand thesenormally solid polymers have greater consistencies.

The metallic color former present in the poly-a-olefin polymericcomponent of this invention is usually, but not necessarily, metallic,polymerization catalyst residue. Me-

' tallic, polymerization catalysts commonly employed in the synthesis ofpoly-u-olefin polymers usually comprise one or more metals in free formor in chemically combined form. While many of the known metals in thePeriodic Table have been suggested for use in a-olefin polymerizationcatalysts compositions, commonly employed metals include titanium,chromium and nickel. These three metals, at least, form coloredcomplexes with bisphenol antoixidants in poly-a-olefin plasticcompositions.

The concentration of the metallic color former in the polymericcomponent is usually small enough to be regarded as a traceconcentration. In general the total metallic content of thepoly-a-olefin polymeric component is less than about 0.1 Weight percentof the polymeric component. For example, the titanium concentration inmany poly-a-olefin polymers is of the order of 0.001 weight percent.

The bisphenol antixoidant component of the plastic composition of thisinvention comprises one or more bisphenol antioxidants. A common type ofbisphenol antioxidant is that represented by the general formula orr OHI If I R- ('J R l R l CH3 on,

3. wherein each R is a radical independently selected from the groupconsisting of hydrogen and hydrocarbon radicals. Typical of this type ofbisphenol antioxidants are 2,2 methylene bis(4 methyl 6 tert.butylphenol) and 2,2 methylene bis[4 methyl 6 (1 methylcyclohexyl)phenol]. A characteristic of the bisphenol antioxidant component of thisinvention is that the absence of admixture of the bisphenol antioxidantcomponent with a poly-a-olefin polymeric component of this inventioncauses the resulting plastic composition to develop a different color.

Concentration of the bisphenol antioxidant component in the plasticcomposition can .vary, depending on the degree of photo-oxidationstabilization desired. Generally, however, the concentration is about0.l1 percent by weight of the composition.

The diethanolamine additive of this invention is characterized by amolecular weight in excess of about two hundred and by being compatiblewith the poly-u-olefin component in that it does not exude therefromafter it is incorporated into the polymeric component. A preferreddiethanolamine additive of this invention is one which is represented bythe general formula:

wherein R is a radical selected from the group consisting of (a)aliphatic hydrocarbon radicals having about 818 carbon atoms and (b)radicals of the. formula i RC-O wherein R is an ali hatic h drocarbonradical having about 7-17 carbon atoms. Readily obtainable compounds ofthis formula (wherein R and R are alkyl radicals are N,Nbis(2-hydroxyethyl)-N+octylamine, N,N-bis(2-hydroxyethyl-N-dodecylamine, N,N-bis Z-hydroxyethyl N-octadecylamine, themonocaproate ester of triethanolamine, the monolaurate ester oftriethanolamine and the monostearate ester of triethanolamine- Thediethanolamine additive functions to suppress the development of adifferent color in the plastic composition. Hence, in this plasticcomposition it is a color stabilizer. The basis for its function isbelieved to reside in its chelating properties. The color stabilizer ofthis inventionis thought to have such an affinity for the metallic colorformer that upon making up the plastic composition from the polyu-olefinpolymeric component, the bisphenol antioxidant component and the colorstabilizer, it effectively prevents the .metallic color former fromreacting with the bisphenol antioxidant to form the aforementioned,highly colored complex.

The concentration of the diethanolaminevcolor stabilizer of thisinvention varies in general with the concentration of the metallic colorformer present in the poly-ixolefin polymeric component. However, anadditive concentration in the plastic composition of about 0.0l0.5weight percent is generally sufficient for good results.

The plastic compositionsof this invention are prepared by incorporatingthe bisphenol antioxidant component and diethanolamine color stabilizerinto the p-oly-a-olefin polymeric component. Generally suchincorporation can be performed by anyone of a number of well-knownmethods, such as roll-compounding, extrusion, solvent-mixing, etc. Forexample, such incorporation can be performed by heating or otherwisesoftening the poly-a-olefin polymeric component to a workableconsistency and then working in as by roll-compounding the bisphenolantioxidant component-and diethanolamine color stabilizer of thisinvention until a substantially uniform mixture or dispersion isobtained. The resulting plastic compositions then are usually cast ormolded into any desired shape, for example, such as pellets, sheeting,films, bars, filaments, articles and the like, as by conventionalcasting and mold- 4 ing techniques which include extrusion, blow moldingand the like.

This invention is further illustrated by the following examples whichinclude specific embodiments thereof. Unless otherwise indicated thisinvention is not limited to these specific embodiments.

EXAMPLE 1 N,N *bis(2-hydroxyethyl-)-N-dodecylamine. In another samplethere was incorporated to the extent of 0.05 weight percent themonolaurate ester of triethanolamine. The third sample contained nocolor stabilizer. Plates were pressed from the samples and subsequentlythe following color observations were made.

Color stabilizer: Color of plate None Yellow N,Nbis(2-hydroxyethyl)-N-(n-dodecyl)- amine Off-white Triethanolaminemonolaurate White No exudation of colorstabilizer from the plates wasobserved. Thus, the diethanolamines of this invention suppress colordevelopment in polyethylene compositions comprising a metallic colorformer and a bisphenol antioxidant.

EXAMPLE 2 A batch of high'density normally solid polypropylene wasobtained which comprised 0.03 weight percent metallic residue of unknowncomposition. Incorporated into three samples of this batch was abisphenol antioxidant marketed as Nonox W5? and chemically identified as2,2-methy lene-bis[ l-methyl 6 (l-methylcyclohexyl)- phenol].Concentration of the antioxidant in each sample was 0.1 weight percent.Incorporated into one sample to the extent of 0.05 weight percent wasN,N-bis(2-hydroxyethyl)-N-dodecylamine. Incorporated into the secondsample at a concentration of 0.05 weight percent was the monolaurateester of triethanolamine. The third sam ple received no colorstabilizer. Plates were pressed from each sample and subsequently colorobservations were made. These observations are set out in the followingtable.

Color stabilizer: Color of plate None Dark amber N,N-bis(Z-hydroxyethyl)N (n-dode'cyl)-amine Off-white Monolaurate ester of triethanolamineCream No exudation of color stabilizer fronrthe plates was observed.Thus, the diethanolamine additives of this example prevent the formationof color in, and are compatible with, polypropylene compositionscomprising a 1 metallic color former and the bisphenol antioxidantdescribed.

EXAMPLE 3 percent the diethanol color stabilizers of this invention,

identifiedin the following table. The fourth sample contained no colorstabilizer. Plates were pressed from each sample and subsequently thecolor of each plate was observed. The following table summarizes thecolor observations.

octyl) -amine Off-White N,N-bis( -hydroxyethyl) N (noctadecyl -amineOfiE-White Triethanolamine monostearate Off-white No exudation orblooming of color stabilizer from the plates was observed. Consequently,the diethanolamine color stabilizers of this invention are effective insuppressing color development of polypropylene compositions containing ametallic color former and comprising the described bisphenolantioxidant.

Thus, there are provided poly-wolefin polymer compositions containingmetallic color formers and bisphenol antioxidants, which are establishedrelative to color development. A feature of advantage is that thediethanolamine additives of this invention are compatible withpoly-ot-olefin polymers and do not exude therefrom.

Other features, advantages and embodiments of this invention will beapparent to those in ordinary skill in the art upon reading theforegoing disclosure. All embodiments of this invention includingvariations and modifications thereof which embrace the spirit andessential characteristics of this invention are within the scope of theclaimed subject matter unless expressly excluded by claim language.

I claim:

1. A plastic composition comprising: (1) poly-a-olefin polymericmaterial prepared from a-monoolefinic aliphatic hydrocarbons having 2-10carbon atoms, containing a metallic polymerization catalyst residue attrace concentration, (2) a bisphenol antioxidant having the formula:

| CH3 C 5 wherein each R is a radical independently selected from thegroup consisting of hydrogen and hydrocarbon radicals, said antioxidantbeing present in a stabilizing amount, and (3) a diethanolamine havingthe formula:

wherein R is a radical selected from the group consisting of (a)aliphatic hydrocarbon radicals having about 8-18 carbon atoms and (b)radicals of the formula:

wherein R is an aliphatic hydrocarbon radical having about 7-17 carbonatoms, said diethanolamine being compatible with said poly-a-olefin andpresent in a color stabilizing amount.

2. A plastic composition according to claim 1 wherein said bisphenolantioxidant is present in a quantity of about 0.1 to 1 weight percentand said diethanolamine is present in a quantity of about 0.01 to 0.5weight percent.

3. A plastic composition according to claim 1 wherein the poly-a-olefinpolymeric material is normally solid polyethylene.

4. A plastic composition according to claim 3 wherein saiddiethanolamine is N,N bis(2-hydroxyethyl)-N-dodecylamine.

5. A plastic composition according to claim 3 wherein saiddiethanolamine is triethanolamine monolaurate.

6. A plastic composition according to claim 1 wherein the poly-ot-olefinpolymeric material is normally solid polypropylene.

7. A plastic composition according toclaim 6 wherein the diethanolamineis N,N-bis(2hydroxyethyl)-N-octylamine.

8. A plastic composition according to claim 6 wherein the diethanolamineis N,N-bis(2-hydroxyethyl)-N-octadecylamine.

9. A plastic composition according to claim 6 wherein saiddiethanolamine is tn'ethanolamine monostearate.

10. A plastic composition as in claim 1 wherein the bisphenolantioxidant is 2,2'-methylene-bis [4-methyl-6- l-methylcyclohexyl)phenol] 11. A plastic composition according to claim 10 wherein saiddiethanolamine is triethanolamine monolaurate.

12. A plastic composition according to claim 10 wherein thediethanolamine is N,N-bis(2-hydroxyethyl)- N-dodecylamine.

References Cited UNITED STATES PATENTS 2,476,554 7/ 1949 Lincoln 260-6442,829,121 4/1958 Leeper 26045.9 2,985,617 5/1961 Salyer et al. 26045.93,013,997 12/ 1961 Coler et a1. 26045.9

DONALD E. CZAJA, Primary Examiner.

LEON I. BERCOVITZ, Examiner. H. -E. TAYLOR, Assistant Examiner.

1. A PLASTIC COMPOSITION COMPRISING: (1) POLY-A-OLEFIN POLYMERICMATERIAL PREPARED FORM A-MONOOLEFINIC ALIPHATIC HYDROCARBOSN HAVING 2-10CARBON ATOMS, CONTAINING A METALLIC POLYMERIZATION CATALYST RESIDUE ATTRACE CONCENTRATION, (2) A BISPHENOL ANTIOXIDANT HAVING THE FORMULA: